Present day businesses expend great amounts of financial and personal resources in attempting to locate and manage objects, including records, equipment, and people. However, present day recordkeeping systems are ineffective at locating these objects.
Many objects must be located quickly to save loss of life and property. For instance, in the hospital setting, patients who are critically ill can best be treated when their physician has their complete medical record in hand. Oftentimes, their records are not available to the treating physician because they have been lost or misplaced. The cost and time dedicated to finding them becomes expensive and potentially life-threatening.
When conditions are not life-threatening, losses are incurred by the health system as a whole, since extra tests are given, delays in diagnosis occur, and major delays in billing result because, for periods of time, these records are lost and cannot be found.
One attempt at tracking file folders, for example, is given in U.S. Pat. No. 5,287,414 whereby an optical scanner mounted to the file drawer is used to detect files stored in the filing cabinet so that, upon opening or closing the filing cabinet drawer, all the files in that drawer are scanned. The scanned folders are logged as being located in that drawer by a computer system. A major drawback of this system is its inability to account for files unless they are located within a filing cabinet drawer.
Attempts at tracking materials and people have also been made, for example, in U.S. Pat. No. 5,363,425, whereby an identification badge containing a radio frequency transmitter is located across a telephone network by receiver units in or near telephone sets. However, this invention teaches the use of random transmissions from the identification badges, which is not applicable to systems containing a number of transmitters because of overlapping or “colliding” of transmission bursts.
An attempt at tracking persons was made by an infrared active badge as described in the December 1993 Byte article “Track People With Active Badges”. This reference teaches the use of infrared transmitters because of their ready availability in television and video recorders and because the signals bounce off of walls which compensates for their directivity. However, the infrared technology disclosed is inadequate for applications where the transmitter is covered by a surface which blocks transmission of infrared light. This design also requires more receivers per installation due to the opacity of objects to infrared light.
Therefore, there is a need in the art for an inexpensive tracking system for a collection of objects which is capable of tracking a large number of objects. Such a tracking system must be able to track objects within an entire room or group of rooms and detect objects even if there is no clear optical path between the beacons and the detecting system. There is also a need for a low power, low cost beacon design to control the overall cost of the tracking system. Additionally, there is a need for a system having a minimal number of receivers to control the cost of the system and the invasiveness of the installation, and the receivers should have an effective means for transferring information to a central processor for processing location information.